Method of and means for insuring a constant or desired let-off tension for the warp in looms for weaving



Nov. 29, 1932. s. A. SHORTER 1,389,266

METHOD OF AND MEANS FOR INSURING A CONSTANT OR DESIRED LET-OFT. TENSION FOR THE WARP'IN LOOMS FOR WEAVING Filed Oct. 2, 1930 2 Sheets-Sheet l Nov. 29, 1932. s. A. SHORTER 1,889,266

METHOD OF AND MEANS FOR INSURING A CONSTANT 0R DESIRED LET-OFF TENSION FOR THE WARP IN LOOMS FOR WEAVING Filed Oct. 2, 1930 2 Sheets-Sheet 2 //v v E N TOR: SYDNE IQLFRED SHORTLY? Patented Nov. 29, 1932 UNITED STATES PATENT QFFiCE S YDNEYALFRED SHORTER, 0F DIDSBURY, MANCHESTER; ENGLAND, ASSIGNOR TO THE BRITISH COTTON INDUSTRY RESEARCH ASSOCIATION, OF DIDSBURY, MANCHESTER,

ENGLAND METHOD on AND Means non INSURING- A CONSTANT on nnsrnnn LET-OFF TENSION non THE WAR]? 11v LOOMS non WEAVING Application filedoctober 2, 1930, Serial No. 485,840, and in Great Britain. November 5, 1929.

These improvements concern a method of and means for automatically maintaining a constant or regulatable let-off tension for warp ends in looms for weaving.

Myinvention has reference to the maintenance of constant or obtainment of a de sired tension on warp during the progress of weaving and is applicable to looms in which the let-off is of the so-called negative type, that is to say, where the forward rotation of the beam is resisted by frictional forces imposed by some suitable mechanism. In an ordinary loom with such mechanism, the tension of the warp, tends to increase during the progress of the weaving owing to the decrease of diameter of the warp on the beam and consequent diminished power of the warp tension to overcome the frictional forces, and it is customary to make periodic adjustments by hand of the friction-producing mechanism, so as to obviate this tendency.

According to my method such manual adjustments are rendered unnecessary, and a constant or desired tension according to requirements is obtained automatically from the disposition at any particular time of the stretch of warp leaving the beam and acting through provided mechanical means combined in the loom to insure uniform tension as the warp is gradually pulled off the beam.

I propose to pass the warp from the beam over a movable bar or roller or other contrivanee, which is linked up by means of levers or other appliances to the friction-producing mechanism in such a manner that the action of the warp on the bar or roller or other contrivance is made to proportionately or otherwise influence the frictional retardation of the beam, the transference of the action being mechanically advantageous, so that a small. change in the action of the warp on the bar or roller or contrivance may produce a relatively large change in the frictional retardation of the beam, in this way,

and I propose to make use of the change of slope of the warp passing to the bar or roller or contrivance to produce a change in the action of the warp, which change, acting through the interposedmechanica-l devices,

can thereby produce such a-diminution of the frictional resistance that the let-off ten.- sion is not increased in spite of the diminished diameter of the warp on the beam. By my invention having the mechanical advantage of the interposed mechanical devices greater than necessary, to cause the let-off tension to diminish during the weaving, but in general I should arrange matters so that the warp tension would remain as nearly as possible constant.

The accompanying drawings illustrate ex-' amples of the application of the invention to looms of ordinary description and they serve to further explain the proposedmethod of automatically and proportionately regulating the loading of the warp threads as the contents of the beam are consumed.

In the said drawings Fig. l is a broken rear elevation, showing the simplest mechanism for mechanically linking the floating bar or roller so that the frictional resistance can be diminished at the necessary rate as the weaving proceeds.

Fig. 2 shows an end "iew of Fig. 1. 7

Figs. 3 and at are detail plan and side elevation of combining weighting parts not illustrated in position by Figs. 1 and 2.

Fig. 5 indicates a modified way of applying a friction chain around a large diameter ruffle in connection with a warp beam.

Respecting the Figs. 1 to 4:, these illustrations are intended to indicate the case of an ordinary Lancashire loom with a single Warp beam a with its trunnions a supported in bearings a attached to the looms sides (1 the warp beams having ruffles a One end only of the loom is shown by'Figs. 1 and 2 as is obvious. The friction on the Warp beam it would be even pcssible by 4 a is produced by chains 6 passed around the rufiles a, one end of each chain being anchored at b to the frame-work of the loom whilst the other end is connected at b to one arm of a bell-crank lever a connected to other parts in a manner to be later described.

At the back of the loom and below the warp beam is a shaft 03 mounted in bearings (1 formed in brackets (Z fixed to the side frames of-the loom, and this shaft (Z is parallel to the axis of the warp beam a.. Such shaft, can for convenience be made square in section (with round portions to fit the requisite bearings) as thereby, various arms or levers (to be later described) can be non-rotatably fitted and are rendered lengthways adjustable in easy fashion. Such arms and levers would have bosses furnished with square holes to fit the square shaft d, thus facilitating the adjustment-and fixing upon the square shaft by set-screws. The use of a square shaft and of square apertures in the bosses of the arms or levers to be ailixed to the shaft is in the nature of a detail.

'Upon the shaft d'I apply the arms which support the bell-crank levers 0, such arms having a boss 6 to fit the square shaft cl, and, extension arms 0 which are round in crosssection for the purpose of supporting the bell-crank levers 0, such bell-crank levers having boss-like central portions bored to fit and turn upon the round arms 6 Upper and loweradjustable stop collars f, f are applied to the round arms 0 between which, the supported bored boss of the bell-crank levers 0 can turn. Also such stop collars 7, f can be readily adjusted to locate the bored boss of the bell-crank lever c in the required position on the round arm a".

a The bell-crank levers c are connected one to the other by a rod 0, the inturned ends of which can hook into holes or slots in said bell-crank levers; or a chain, or rod and chain may be used As already stated, the ends 6 of the rufile chains 6 are connected to the bell-crank levers c; The said bellcrank levers c, and the coupling tie therefor, could be made in various forms so long as they serve as means for preventing inequalities in the tension of the chains 6 by crossconnecting the elements to which the attached friction chains 6 are afiixed.

The friction chains I; could be attached directly to the arms 6 by means of terminal rings and hooks, held in place by fixed collars.

Attached to the square shaft d are two lever-like structures 9 preferably made in two or more parts or sections with appropriate slots and connecting bolts for facilitating adjustment or setting of the upper exiremities, and these lever-like structures 9 carry a roller or 'bar 9 which is disposed parallel to the axls of the warp beam a and shaft d, The drawings show a roller or bar 9 working in cup bearings at the top of the lever-like structures 9, but a simple bar fixed relatively to the lever-like structure 9 might be used, and, in such event, allowance would be made in the requisite calculations for the friction on the warp passing over such fixed bar. Obviously I might make use of a composite roller with short axles to it in bearings in the upper ends of lever-like structures similar to g, and such variations are only in the nature of details.

The roller or bar 9 is shown as constituting the actual back-rest, over which the sheet of warp it must pass in going forward to the shedding mechanism. The roller or bar 9 may be used in conjunction with a separate fixed or oscillating back-rest, or it may have an oscillating back-rest fixed upon it or combining with it, or it may consist of a number of bars or rollers with which the sheet of warp intertwines.

The manner of arranging the chains Z) around the ruilles a, shown in Fig. 2, is the most suitable for ruffles of small diameter. In the case of rufiles of large diameter the arrangement shown in Fig. 5 is ordinarily the more convenient, and the chains 5 are indicated as being anchored at the points 6 and connected to the bell-crank lever c at 6 To tension the chams b, b i may use any known means of applying an adequate torque to the shaft (Z. With the parts constructed and arranged, as in Fig. 2, the torque requires to be in a clock-wise direction. A deadweight system of applying the requisite torque is indicated in detail plan view, Fig. 3, and in elevation by Fig. 4. Arms 6 are fixed on the shaft d so as to project in a horizontal direction rearward of the loom. For light weightings, weights could be attached directly to such arms 2', but in general it will be desirable, in order to avoid excessively heavy weights or an inconvenient length of arm 2', to indirectly combine the weights say by some such arrangement as that shown. Proj ecting horizontally and rearwardly from the brackets d are bars d which are circular in cross-section and such bars (Z serve each as the pivotal support for the weighting lever provided with adjustable weights The weighting levers fact on adjustable hooks i, which hook on to the extremities of the arms 2', the bosses of which, as already stated, are fixed on the shaft d. In this weighting arrangement the two weights do not act separately on the corresponding chains Z), but together produce a torque, the part of which not borne by the warp passing over the roller or bar 9 is transmitted equally to the two chains by means of the levers 0 and rod 0 Any other appropriatev system of dead weighting may be utilized. As for example, I might have horizontal arms attached to the shaft (Z and running towards the front of the loom. to be acted upon in an upward direction by. suitably arranged weighting levers.

ing eflectat any stage of the weaving.

Again, the tensioning' of the: friction chains (such as 6) might: be effected by mechanical combinations, including! helical or other sprmgs.

In the drawings, the shaft cl is shown derneath the: beam. This arrangement ismost. suitable for an ordinary Lancashireloom with a single beam. With other types of loom and of beam, it maybe more convenient' to fix the shaft CZ above the beam.

As regards tension release. When: it is desired to move the Warp beam round by hand, all that is required is, to rotate the shaft (Z through a small angle (anti-clockwise in Fig. 2) so that the tension is: taken off the friction chains. For very light tensions, this may be done by pulling or pushingagainst the floating roller or bar 9 and retaining it by a suitable catch. In most cases, however, such a: procedure would re quire considerable strength, and therefore I should make use of any known device for rotating the shaft (5 through a small angle, and retaining it, while the beam is being operated on. Y

In weaving certain types of cloth, it is sometimes the custom to apply increased friction-al resistanceat certain points in the cycle of loom operations, for example at the beat up. There are many known appliances for doing this. Such devices can if required be used in conjunction with my invention and arranged so as to act on a pulley or other appliance attached either to the beam or to the shaft (Z.

Having now described in detail particular applications of my invention I will proceed to explain its nature and mode of action.

The use ofa floating roller whereby a portion of the applied weighting is taken away from the friction producing mechanism is not novel, there being numerous inventions involving such use. The novelty of my invention lies in the fact that my mechanical arrangements are such that the change of slope of the portion of the warp passing from the beam to the roller insures a sufliciently correct and uniform weight The essential features of my mechanism have been deduced from a mathematical-analysis of the motionbearing the following considerations in mind. It is generally main? tained, in patent specifications describing such inventions, that during each cycle of loom operations the warp tension increases till the weighting is removed from the chains, after which a small amount of yarn is let off the beam so that the warp tension diminishes and the chains are again tensioned. If this view were correct, the warp tension would simply be the tension necessary to support the entire weighting, and would be independent of the diameter of the warp on the beam. This view is, however, incorrect,

but does not for in accordance with the dynamical prin ciples, left-oil: of the Warp occurs before the entire: weighting is removed from the chains. It. occurs at the point when the actual warp tension becomes equal to the necessary let- 01f tension- This point is not the same for all diameters of the warp on the beam. When the diameter is small more weight must be. removed from the chains, than when it is. large, so that the elfective pull of the warp on the floating roller must be greater in the former case than in the latter. I11 previous inventions this increased pull is obtained by an increase of the actual tension of the warp. The consequence is that as the warp weaves down the warp tension increases and so removes some of the weighting from the chains, with the result that the progressive increase of warp tension is not so great as would correspondto the diminution of the diameter of the warp on the beam. ner of'these previous inventions, mitigates,

cure, the increase of warp tension caused by the diminution of the diameter of the warp on the beam.

The novelty of my invention lies in the fact that I obtain an accurately graduated increase in the friction-relieving effect without any increase in the warp tension, the warp tension for all let oils being a con stant force. It will be seen from Fig. 2 that as the beam weaves down the warp sheet it changes in slope with respect to the arms 9 so as to exert an increased effective pull on the floating roller, that is, so that the same warp tension exerts an increasing friction relievingelfect. The actual amount of increase of friction-relief between any two stages depends upon how much dimunition of chain tension is produced by the increased pull of the warp on the roller, and this depends upon the mechanical advantage of the cranked lever formed by the roller arms 9 and the chain arms 6 that is to say, on the ratio of the length of the arms 9 to the effective length of the arms 6 as determined by the position of the bell-crank levers c. From a knowledge of the angles which the warp sheet it makes with the plane of the roller arms 9 at two stages of the weaving, say at the full and at the nearly empty beam, and of the relation between the warp let-off tension and the chain tension, we can readily determine the position of the bell-crank levers c which will give the same let-ofl tension at the two stages.

The bell-crank levers 0 may thus be set so as to give the same let-ofl tension at the beginning and the end of the weaving but it does not necessarily follow that it will be the same at all intermediate stages. In my invention I insure a constant tension at intermediate stages by so arranging the angle which the warp sheet it makes with the plane Afloating'roller, used in the manof the lever arms 9 that it does not differ much from the angle it makes with the plane containing the axes of the beam and the roller 9 The strict theoretical requirement is that these angles should be equal, that is to say, that the plane of the roller arms 9 should pass through the axis ofthe beam, but the degree of approximation shown in Fig. 2 is good enough for practical purposes. The necessity for this arrangement lies in the fact that the equal increments of the pull of the warp on the roller correspond to equal decrements of the sine of the former of the two angles mentioned above, while equal decrements of the diameter of the warp on the beam correspond to equal decrements of the sine of the latter angle.

The necessity for this latter arrangement is most simply realized by considering an arrangement in which the shaft cl is placed above the beam so that the arms 9 are nearly horizontal. The change of slope of the warp sheet h would still be such that the efiective pull on the roller would be greater at the end of the .beam than at the beginning, and this pull could be transmitted to the chains at such a mechanical advantage that the warp let-off tension is the same at the end as at the beginning, but there would be an appreciable variation at intermediate stages. If the warp sheet h is near'the position at which it madea right angle with the plane of the roller arms 9, the pull on the roller would be practically constant, so that the warp tension would increase.

I declare that, what I claim is: I

1. In a device for the purpose described, a revolubly mounted warp beam provided with friction cylinders at its ends, a pair of levers arranged one at each end of the warp beam,

said levers each having one end pivoted to 7 swing on an axis common to both levers, a back rest bar carried by the free ends ofboth arms and positioned to have the warp sheet from said beam pass directly to and thereover, a revoluble shaft whereto the pivot ends of said arms are fixed,.friction chains each extending around a respective friction cylinder and having one end fixed, a pair of rock arms fixed on said shaft, operative connections between the respective chains and the respective arms of said pair and including means to equalize the respective stresses on the chains, and means to urge said arms away y from said cylinders whereby to tension said chains. 7 I

2. In a device for the purpose described, a revolubly mounted warp beam provided with friction cylinders at its ends, a pair of levers arranged one at each end of the warp beam, said levers eachhaving one end pivoted to swing on an axis common to both levers, a back rest bar carried by the free ends of both arms-and positioned to have the warp sheet from said beam pass directly to and thereover, a revoluble shaft whereto the pivot ends of said arms are fixed, friction chains each extending around a respective friction cylinder and having one end fixed, a pair of rock arms fixed on said shaft, bell crank levers each pivoted at its angle on a respective arm and each having one of said chains connected to one of its legs, a link connected at its ends to the remaining legs of said bell crank levers, and means to urge said arms away from said cylinders and thereby tension said chains.

3. In a device for the purpose described, a revolubly mounted warp beam provided with friction cylinders at its ends, a shaft extending parallel to and positioned substantially in vertical alignment beneath the axis of the beam, levers fixed on said shaft and arranged one at each end of the beam, said levers extending upwardly above the beam and in proximity to the axis of the beam at one side thereof, a bac rest bar carried by the upper end of the levers to permit the warp threads to extend from the beam on the same side of the axis as the levers directly to the bar and to run over said bar,-a pair of arms each fixed to the shaftopposite a respective cylinder, chains extending around said cylinders and each having one end fixed, operative connections between the respective chains and arms, and means to urge saidarms away from said cylinders whereby to tension said chains.

4. In a device for the purpose described, a revolubly mounted warp beam provided with friction cylinders at its ends, a shaft extending parallel to and positioned substantially in vertical alignment beneath the axis of the beam, levers fixed on said shaft and arranged one at each end of the beam, said levers extending upwardly above the beam and in proximity to the axis of the beam at one side thereof, a back rest bar carried by the upper end of the levers to permit the warp threads to extend from the beam on the same side of the axis as the levers directly to the bar and to run over said bar, a pair of arms each fixed to the shaft opposite a respective cylinder, chains extending around said cylinders and each having one end fixed, operative connections between the respective chains and I arms and including means to equalize the respective stresses on the chains, and means to urge said arms away from said cylinders whereby to tension said chains.

5. In a device for the purpose described, a revolubly mounted warp beam provided with friction cylindersat its ends, a shaft extending parallel to and positioned substantially in vertical alignment beneath the axis of the beam, leversfixed on said shaft and arranged one at each end of the beam, said levers extending upwardly above the beam and in proximity to the axis ofthe beam at one side thereof, a back rest bar carried by the upper end of the levers to permit the warp threads to extend from the beam on the same side of the axis as the levers directly to the bar and to run over said bar, a pair of arms each fixed to the shaft opposite a respective cylinder,- chains extending around said cylinders and each having one end fixed, bell crank levers each pivoted at its angle on a respective arm} and each having one of said chains connected to one of its legs, a link connected at its ends to the remaining legs of said bell crank levers,- and means to urge said arms away from said cylinders and thereby tension said chains;

In testimony whereof I have signed my name to this specification.

SYDNEY ALFRED SHORTER 

